Ohm's Law Formula

The Formula

V = IR or equivalently I = \frac{V}{R} or R = \frac{V}{I}

When to use: More push (voltage) means more flow (current). More resistance means less flow for the same push.

Quick Example

A 12 V battery connected to a 4 \Omega resistor: I = \frac{12}{4} = 3 A.

What This Formula Means

The relationship stating that voltage across a conductor equals the current through it multiplied by its resistance.

More push (voltage) means more flow (current). More resistance means less flow for the same push.

Worked Examples

Example 1

easy
A 12 \text{ V} battery is connected to a 4 \text{ } \Omega resistor. What current flows?

Solution

  1. 1
    Apply Ohm's law: I = \frac{V}{R}.
  2. 2
    Substitute the values: I = \frac{12}{4}.
  3. 3
    I = 3 \text{ A}

Answer

I = 3 \text{ A}
Ohm's law (V = IR) is the fundamental relationship in circuit analysis. It connects voltage, current, and resistance in a simple linear relationship.

Example 2

medium
A heater draws 5 \text{ A} from a 240 \text{ V} supply. What is its resistance, and how much power does it consume?

Why This Formula Matters

Ohm's law is the most-used equation in circuit analysis and electrical engineering.

Frequently Asked Questions

What is the Ohm's Law formula?

The relationship stating that voltage across a conductor equals the current through it multiplied by its resistance.

How do you use the Ohm's Law formula?

More push (voltage) means more flow (current). More resistance means less flow for the same push.

Why is the Ohm's Law formula important in Physics?

Ohm's law is the most-used equation in circuit analysis and electrical engineering.

What do students get wrong about Ohm's Law?

Ohm's law applies to individual components, not always to the whole circuit at once.

What should I learn before the Ohm's Law formula?

Before studying the Ohm's Law formula, you should understand: voltage, resistance, electric current.

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